Process for deburring and polishing



Jan. 25, 1966 J. F. RAMPE 3,230,671

PROCESS FOR DEBURRING AND POLISHING Filed Sept. 23, 1963 2 Sheets-Sheet 1 F16. I suns VIEW F VIBRRTORY MACHINE TUB I800 ORB/T5 I600 I400 PER I200 U MIN TE I000 o 6o 15 90 m; /20

unpszo TIME MINUT5 RELATIVE cur DEPTH 0 EMS 3 OUT 20 warm "o 1; so 45 /20 ELAPSED TIME mwu'ras 7 START/N6 4o SURFACE I HNHL CUT sunmcc DEPTH 0 5CTION OF MTAL SURF/I06 WWW 0 I5 30 45 e0 75 90 I05 /2o ELHPSED TIME MINUT$ INVENTOR.

Jan. 25, 1966 J. F. RAMPE 3,230,671

PROCESS FOR DEBURRING AND POLISHING Filed Sept. 23, 1963 2 Sheets-Sheet 2 I600 ORB/T5 PEI? I400 MINUTE 1 I000 B I ELHPSED TIME MINUTES STHRTING 40 l I CUT '1 v I /f/ /4 I j I I secT/orv OF METHL SURFACE 0 I5 30 45 6o I05 I20 ELFIPSED TIME MINUTES United States Patent 3,230,671 PROCESS FOR DEBURRING AND POLISHING John F. Ramps, 3417 Fairfax Road, Cleveland Heights, Ohio Filed Sept. 23, 1963, Ser. No. 310,613 4 Claims. (Cl. 51313) This invention relates to deburring, polishing and related methods for the finishing of ferrous and nonferrous parts in vibratory and/or tumbling barrels and the like wherein abrasive action is the basis for surface improvement as it grinds away rough spots, burrs, sharp edges, etc.

The object of this invention is to perform such finishing through the initial rough cutting stages to the final polishing stages, with the greatest efficiency, notably by using a single rough cutting abrasive medium throughout, and without changing or reloading the equipment with finer and finer cutting and polishing media.

A further object of this invention is to supply an accurate, scientific control of this cutting and polishing action, so that it can be duplicated at will on subsequent occasions.

Abrasive removal of superfluous material is related to the coarseness, .grit and grain size of the abrasive media, and also to the kinetic energy expended. The greater the coarseness, the more aggressive the cutting ability. The more kinetic energy expended, the faster and deeper the cutting action of the abrasives becomes. In the case of orbital vibratory finishing, the faster the speed of the orbit, the more deeply the abrasive will cut, the greater the forces and pressures of the media to the work parts, and the greater the rate of abrasive action.

When work parts are subjected to relatively high degrees of abrasiveness and kinetic energy, faster cuts and rougher surfaces will result. As these conditions are reversed, i.e., the smoother and less aggressive the finishing action becomes, smoother and lower micro finishes will result. 1

Other objects, advantages and features of the inven tion will become apparent as the description proceeds, this description being made in connection with certain diagrams, figures and charts which appear in the accompanying drawings.

In the drawings:

FIGURE 1 is a diagrammatic side view of a vibratory tub loaded with media and work parts, in process of vibratory finishing action:

FIG. 2 shows graphically the relationship of orbits per minute and elapsed time in the vibratory finishing process;

FIG. 3 shows graphically the variation of the cutting depth of the media on the work parts in relation to the orbits per minute, or kinetic energy input;

FIG. 4 shows graphically the progress of decreasing cut depth in relation to time and/or decreasing orbits per minute;

FIG. 5 shows graphically the relation of orbits per minute in relation to elapsed time, where abrupt change is made in orbits per minute; and

FIG. 6 shows graphically the abrupt and undersirable refinement of cut depth which occurs when abrupt speed change is made as in FIG. 5.

FIGURE 1 shows diagrammatically a side view of a suitable vibratory machine such as may be used in practising the process of the present invention and on which can be demonstrated or shown as by circular arrows the orbital paths of abrasive media used in this process. A suitable mechanism is disclosed in prior US. Patent No. 3,191,348, granted on application Serial No. 261,981, filed March 1, 1963 and entitled Apparatus :for Orbital Finishing. This machine has a tub which is orbited in a "ice small circle (Ms inch diameter) by the ofi? center crankshaft mechanism of the machine. Note the circular orbit cior each media particle and the general rotary flow path of entire load of media in the tub. As the orbits per minute increase, the speed and centrifugal force of the media particle increase. As the orbits per minute decrease, the opposite is true. The media particle with lessened force does not cut in a furrow or scratch as deeply as before. This lessened cutting depth results in a smoother or lower micro inch finish, which is really what polishing is.

The vibratory machine is power driven and preferably has an orbital speed range of from about 900 to about 1800 orbits per minute. Time is controlledby a suitable automatic timer for precise quantitative results of the abrasive action, although manual control is also contemplated.

The abrasive medium may be of various compositions, shapes and sizes; it may be random crushed or it may be of preformed bonded shapes such as triangles, spheres or cylinders. It may comprise aluminum oxide, silicon carbide or mixtures thereof. Preferably the largest practical sizes are used, being those which in operation are small enough to rub against all surfaces of the work pieces that are to be treated. Larger media shapes cut much faster than smaller shapes.

Parts finished by this process to advantage are forgings, stampings and machined turned parts. Because of the nature of the manufacturing processes and tooling details, such parts have rough and uneven surfaces, sharp corners and burrs resulting from cutting and drilling. Sizes generally are not larger than about 5 inches in any direction, but this is not a limiting factor, as the part to be finished can eifectively be close to the volume size of the particular vibrating tub available. Parts encounrtered in practice are generally ferrous, other materials may require other media. The chemical compound in the water flowing through the tub and flushing out the abrasive fines and abraded material is selected to be compatible with the special work parts being finished.

FIGURE 2 is a graph showing the relationship of orbits per minute and elapsed time in the process. It is shown that from A to B on this graph the work parts are most aggressively abraded at high orbital speed which is in direct proportion to the kinetic enegry input to the machine, in horsepower. Beginning at B the speed of orbits per minute is reduced by 50, then again and again every ten minutes the speed is reduced by 50 additional orbits per minute. This speed reduction can be done by hand adjustment, by automatic timer control or, as in the case of the dotted line from B to- C, by suitable stepless automatic mechanical control.

Relating FIGURE 2 to FIGURE 3 it is shown that the cutting depth of the media will vary in relation to the orbits per minute, or kinetic energy. This is further translated from out depth to smoothness, surface polish and R.M.S. values. See FIGURE 4.

This finishing process can be accomplished from very rough surfaces to fine polished surfaces of 5 R.M.S. or less. Time is the factor for degree of accomplishment.

In the event that the virbratory tub is operated at high orbital speed from A to B, FIGURE 5, then slowed down to a fixed speed from B to C, the desired results will not be obtained. The surface finish will be as shown in FIGURE 6 which still preserves all of the original roughness.

This invention is thus capable of being used in connection with conventional orbital finishing machines. For a set initial period of time preliminary rough cutting takes place with coarse abrasives and high orbital speed of the order of about 1800 orbits per minute; a high apmass in the tub are related to finishing, thus the reduction of either will produce finishing of lower micro inch surfaces as is desired.

The present invention is not limited to the particular apparatus referred to or to the precise steps of the process described, it being understood that the details set forth are given for purposes of illustration and example without intending to be limited thereby; numerous modifications of and chances in the procedure are contemplated and intended to be included within the scope of the claims.

What is claimed and desired to be protected and secured by United States patent is:

1. In the process of finishing work pieces by abrasive action in which the Work pieces are commingled with abrasive media to form a heterogeneous mass and the mass is subjected to orbital motion, the improvement which comprises moving all portions of the mass simultaneously over orbital paths, the magnitude of each of which is of the order of about inch at a rate of about 1800 orbits per minute for an initial period of about 45 minutes, continuing the orbital movement of the mass for a terminal period and, during said tenminal period, progressively reducing the orbital rate.

2. A finishing process as defined in claim 1, the terminal period of the orbital movement being at least substantially equal in duration to the initial period.

3. A finishing process as defined in claim 1, the orbital motion being reduced during the terminal period at a substantially uniform rate.

4. A finishing process as defined in claim 1, the orbital motion at the end of the terminal period being at the rate of about 900 orbits per minute.

References Cited by the Examiner UNITED STATES PATENTS 2,387,135 10/1945 Fruth 513l5 2,997,813 8/1961 Brandt 5l-7 3,108,408 10/1963 Dahlquist et a1. 51-l63 LESTER M. SWINGLE, Primary Examiner. 

1. IN THE PROCESS OF FINISHING WORK PIECES BY ABRASIVE ACTION IN WHICH THE WORK PIECES ARE COMMINGLED WITH ABRASIVE MEDIA TO FORM A HETEROGENEOUS MASS AND THE MASS IS SUBJECTED TO ORBITAL MOTION, THE IMPROVEMENT WHICH COMPRISES MOVING ALL PORTIONS OF THE MASS SIMULTANEOUSLY OVER ORBITAL PATHS, THE MAGNITUDE OF EACH OF WHICH IS OF THE ORDER OF ABOUT 1/8 INCH AT A RATE OF ABOUT 1800 ORBITS PER MINUTE FOR AN INITIAL PERIOD OF ABOUT 45 MINUTES, CONTINUING THE ORBITAL MOVEMENT OF THE MASS FOR A TERMINAL PERIOD AND, DURING SAID TERMINAL PERIOD, PROGRESSIVELY REDUCING THE ORBITAL RATE. 